TOF Camera Laser Diode Control for Detection Range
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Solution Overview
Problem
Existing TOF cameras have a limited detection range due to the use of light emitting diodes as light sources, and when switching to laser diodes, the high peak power requires a long cooling time, making it difficult to operate them at fast modulation times.
Innovation Solution
A TOF camera system that uses a control unit to sequentially operate multiple laser diodes according to a modulation signal, adjusting their driving order and current values to improve detection range and tolerance to external light, thereby compensating for the long duty cycle of laser diodes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a laser diode is used as a light source instead of a light emitting diode, then the detection range is improved and tolerance to external light is enhanced, but the laser diode requires a long cooling time due to high peak power, making it difficult to operate at fast modulation times
Solution Approach 1:
The patent divides the light emitting function into multiple laser diodes (first laser diode and second laser diode) that operate sequentially. Each laser diode has a longer duty cycle individually, but together they achieve the required fast modulation speed. The control unit alternates between activating the first and second laser diodes, effectively segmenting the light emission duty cycle across multiple components.
2Power
If a laser diode is operated in pulse mode to achieve high peak power, then the detection range is improved, but the cooling time increases, reducing the effective duty cycle
Solution Approach 1:
The patent ensures continuous light emission by alternating between the first and second laser diodes. While one laser diode is emitting light, the other is cooling down. This continuous switching maintains uninterrupted light output for detection while allowing each individual laser diode to cool during its inactive phase, effectively eliminating dead time.
3Measurement precision
If multiple laser diodes are operated sequentially according to modulation signal, then the detection range is enhanced and external light tolerance is improved, but the device complexity increases
Solution Approach 1:
The control unit receives a modulation signal from the light receiving unit and uses this feedback to determine the driving order and current values of the laser diodes. The system adjusts the operation of the first and second laser diodes based on real-time feedback from the detection process, enabling adaptive control that maintains optimal performance while managing complexity through intelligent signal processing.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The system enhances the detection range and tolerance to external light, improving the performance of the TOF camera by efficiently managing the operation of laser diodes, allowing for improved distance calculation and reduced interference.
Implementation Method 1
a light source that emits light having a predetermined center wavelength, and the light source modulates emitted light with a predetermined frequency
Implementation Method 2
the light source modulates emitted light with a predetermined frequency
Implementation Method 3
the light irradiated to the object is reflected and is returned to the TOF camera
Implementation Method 4
the TOF camera compares a phase of the emitted light with a phase of the light reflected and returned from the object, thereby calculating the distance to the object
Implementation Method 5
The light receiving element 14 converts light energy into electrical energy
Data Source
AI summary
A TOF camera for a vehicle includes a light emitting unit that irradiates light to an object, a light receiving unit that detects a distance to the object based on light reflected and returned from the object and generates a modulation signal for frequency modulation of the light, and a control unit that controls driving of the light emitting unit according to the modulation signal of the light receiving unit. The light emitting unit includes a plurality of laser diodes. The control unit decides a driving order of the laser diodes according to the modulation signal of the light receiving unit so as to control driving of the laser diodes, and decides current values of the laser diodes according to the modulation signal of the light receiving unit so as to control current amounts of laser diodes to be driven.